Drill-grinding machine



2 Sheets-Sheet 1.

(No Model.)

0. WALKER. DRILL GRINDING MACHINE.

Patented Oct. 1, 1889.

l! ennui V i 4, (I w 1.

(No Model.) v 2 Sheets-Sheet 2. 0. S. WALKER.

DRILL GRINDING MACHINE.

,No. 411,845. Patented 00. 1 1889.

] 7217670707? f 7%wflfw N. PETERS PhaloLillwgraphor, Washingiun. D4 0.

PATENT OFFICE.

OAKLEY S. \VALKER, OF \VORCESTER, MASSACHUSETTS.

.DRlLL-GRINDING MACHINE.

SPECIFICATION forming part of Letters Patent No. 411,845, dated October1, 1889, Application filed December 23, 1887. Serial No. 258,925 (Nomodel.)

To all whom it may concern:

Be it known that I, OAKLEY S. VALKER, a citizen of the United States,residing at \Vorcester, county of lVorcestcr, State of Massachusetts,have invented certain 11 ew and useful Improvements inTwist-Drill-Grinding Machines; and I do declare the following to be afull, clear, and exact description of the invention, such as will enableothers skilled in the art to which it appeltains to make and use thesame, reference being had to the accompanying drawings, and to theletters and figures of reference marked thereon, which form a part ofthis specification.

My invention relates to twist-drill-grinding machines, the object beingto produce an improved form of grinding for the end surface of eachdrill-lip.

It has been particularly my object in the invention herein described toproduce a device that does not necessitate the chucking and centering ofthe drills, the operation of the same being obvious to ordinaryunskilled workmen, and the adjustment for each size of drill beingplainly indicated on the ma-' chine.

To this end my invention consists of several novel and valuable featuresof construction, and especially of an improved drill holding andoperating device, hereinafter more fully described. This device is soarranged that the drills are held in place during the grinding operationby their own gravity aided by the hand of the operator, thus effecting asaving of the time usually spent in adjusting the same in a chuck.

This drill holding and operating device consists of a rigid and amovable V-grooved drill-support, a reversible drill-stop, an improvedlip-rest permanently set and adjusted for all sizes of drills, and an angular graduated slide so constructed as to perform the triple duty ofgiving the drill two adj ustments and feeding the same against thegrinding-wheel by means of the same feed-screw.

The device consists, further, of a threaded axis of oscillation uponwhich the correspondingly-threadeddrill-holder swings or oscillatcshelically and gives the drill-lip a screwthread surface or helicoid. Theadvantages of this shape of drill-lip may be briefly enumerated asfollows: If the movement of any point on the surface of the drill-lip befollowed as the drill is fed to its work with a regular feedadvancement, it will be found that the said point will describe a helixof greater orless pitch, according as the feed is accelerated orretarded, and if the drill be stopped in the midst of its cutting theshape found at the bottom of the hole will be a helicoidal instead of aconical surface, and it follows that a drill-lip ground to a helicoidalsurface will be best adapted for cutting under such conditions.

Other devices have been tried heretofore that produce surfaces ofvarious shapes, including right cylinders and cones and various-warpedsurfaces, and machines also that make a'surface approximating a helicoidby means of cams and like devices. The lastnamed class of machines,however, employ an axis that is coincident with the axis of the drill,and the resultant surface leaves-the drill-point rounded on too smallaradius, and the cutting properties of the end of the drill web or pointare in a measure destroyed. The

central web of a twiscdrill is made with a thickness proportionate tothe diameter of the drill, and is necessary to give strength andstiffness to the same; but it forms a point of great resistance to thedrill in cutting, and should be shaped in the best form to make itsscraping action as free as possible. In my invention I aim to grind thispoint on as long a radius as practicable and obtain best results. If adrill-lip be ground on an axis that coincides with the axis of thedrill, and any circular element on this lip-surfaceas, for instance, anelement midway between the periphery and point on a drill of one inchradius-be taken, the radius of this element of surface will be one-halfthe radius of the drill, or will coincide with the radius of the drillat this point. If, however, the axis of the ground surface be conceivedas inclined to the axis of the drill, it is evident that the curvatureof the lip at the periphery may be the same as in the first case, whilethe radius of curvature near the drill-point may be much greater than itwas in the first case, and consequently a drilh point is produced morenearly approximating a straight line and a clearer cutting-point isproduced. I therefore employ an axis of oscillation considerably removedfrom and inclined to the axis of thedrill, and produce a drill-lipsurface of proportionately longer radius at the point than at theperiphery of the drill and a helicoidal surface in contour.

In the accompanying drawings, the same letters indicating like parts ineach, Figure 1 is a side elevation of my twist-drill-grinding machine,shown partly in section. Fig. 2 is a side elevation of the drill holdingand operating device and the grinding-wheel. Fig. 3 -is an end elevationof the swivelhead F, and shows handle F and the projections 19, whichserve as stops for the oscillating drillholder.- Fig. 4 is an endelevation of the V- shaped drill-holder, showing drill in place. Fig. 5is an end elevation of the main supporting-standard, with thedrill-operating mechanism removed and the grinding-wheel in place. Fig.6 is a plan view of the drillholder at a right angle to the top surfaceof the same. Fig. 7 is an enlarged end elevation of drill-holder,showing different-sized drills in place and the lip-rest. Fig. 8 is anelevation of a twist-drill illustrating the peculiarities of my improvedsurface for out- 1 ting lips.

I feather-key not shown.

A is the main standard of the machine, and D the annular grinding-wheel,which is held in place on the taper spindle B by the internally-threadedWasher L. Y

O is the spindle-pulley, and is held by a In the outer end of the pulleyC is screwed a bushing c, abutting against the end of the spindle B andheld by central screw d. By unscrewing bushing a slightly and tighteningscrew cl, the pulley C .is forced farther onto the spindle B andadjustm'ents thus made for wear. The oil-channels' f serve to convey thewaste oil from each end of the spindle to the hollow in the center ofthe standard,where it may be conveyed to a drip-cup. The standard A isbored and fitted with a clamping-screw, operated by the handle K to bindthe cylindrical slide E in any desired position. On one end of slide Eis mounted the swivel-head F, held by the central bolt E screwed tightlyinto the same and maintaining the proper tension.

The swivel-head F is provided with an apertureforming an inclinedsleeve, which is internally threaded for the reception of thesimilarly-threaded shaft G, which is fastened in the guide-bracket G bya set-screw h, and turning with the bracket G moves itself and thebracket along the line a 1), according to the pitch of its screw-thread.On this guide-bracket G is mounted the drill-holder H and its attendantparts. The object of the swivel-head F is to allow the drill-holder tobe moved across the grinding-wheel, parallel to the grinding-surface, todistribute the wear and maintain the truth of thewheel. The cylindricalslide E may be made to perform the functions of the swivel-head F byslightly loosening the clamping-screw K and permitting the cylindricalslide to rotate.

The drill-holder H is provided-attheibottom with anangular slide workingon dovetailed ways on guide-bracket G, and operated by means of thehand-wheel 7c and feedscrew Z.

Graduations n on bracket G indicate the proper position of the slide bythe pointer m for the different-sized drills.

The drill-holder H is provided with a planed guideway, at one end ofwhich is arigid V- shaped support for the drills, and adjustably mountedon the said guideway is the sliding V-shaped support I, held by aset-screw 0',

which is operated by a lever; and also there is likewise mounted thesliding drill-stop J, which is reversible and may be clamped in anyposition by the screw 0.

t is the stationary lip-rest, held in place by screws t. j n n is theline of drill-contact, and is shown inclined to the bisecting line ofthe V? angle, and intersecting the same near the apex: of said angle,the object being to com-,

pensate for the variation in thickness of the drill-points. By thismeans the cutting-edges of all drill-lips placed against the rest areheld parallel to each other. The points numbered 1 2 3 4 5 in Fig. 6show somewhat exaggerated the different po-' sitions of drills of largediameter, in reference to the axis of oscillation, which is fixed at thepoint as.

In Fig. 8 the line 0 d is a somewhat mag- IOC nified representation of ahelix described by ing-screw K is loosened and. the cylindrical slide Eis pulled out and clamped, so that the drill-holder is some distanceaway from the grinding-wheel, and a drill is then laid in the V-shapedsupports, the movable support I and drill-stop J being suitably adjustedfor the purpose, andthe lip of the drill to be ground being placed incontact with the liprestt and extending about an eighth of an inchbeyond it. The drill-holder is then moved by means of the feed-screw Zand hand-wheelie until the pointer indicates on the guidebracket G thegraduation that corresponds to the diameter of the drill being ground.The drill is now held in place by one hand, while the cylindrical slideE is moved until the drill comes in light contact with thegrindingwheel. The cylindrical slide is then clamped rigidly in place,and with. one hand holding the drill the other operates the feed-screw Zby means of the hand-wheel k, and at the same time oscillates the drilland holder until the guide-bracket comes in contact with the stops 1) oneither side. The drill may be re peatedly reversed in the drill-holderwith one hand until both lips be ground exactly alike.

Clearance is obtained on drills ground with my invention by means of thethreaded axis, which advances the drill as it is being ground, and avariation of clearance necessary for varying diameters of drills isobtained by means of the angular slide on the drill-holder H, beforementioned, which carries the drills forward and away from the axis-ofoscillation in regular proportion to their diameters, giving varyingradii of grinding and Varying lateral adjustment for the differentdegrees of clearance required, as clearly shown in Fig. 6.

In Figs. 1 and 2 the diiferent radii of grinding on drills S and S areshown. Theline a b is the axis of oscillation.

The points 1, 2, 3, 4, and 5 indicate different positions of thedrill-points, and the par allel lines drawn to each of these pointsrespectively represent center lines of drills in each position, as thedrill-holder is carried out in the direction e f by the feed-screw Z.

In the foregoing specification I have described an angular slide movingin a direction oblique to the axis of the drill, thus giving the drill alongitudinal and lateral adjustment with but one movement of the slide.The lateral adjustment of the drill, however, may be obtained in anothermanner with my device, as follows: In placing a drill in my groovedV-shaped drill-holder the center of each succeeding drill of largerdiameter will rest higher up in the V-holder, which is obvious, and itis also evident that the centers of all drills will lie in the rightline, which bisects the angle of the V. If the V-holder be inclined awayfrom the axis of oscillation in a lateral direction, this bisecting linewill also be inclined away from the same, and, as the drill-centersalways lie in the bisecting line of the V, they will have an increasedlateral adjustment from the axis of oscillation proportionate to theirincreased diameters, a result precisely similar to that obtained bymeans of the an gularity of the slide previously described, the slide inthis case maintaining the axis of the drills in the same vertical plane.I do not, therefore, confine myself to an angular slide to obtain proportionate lateral adjustment for differentsized drills; but

What I claim as new, and desire to secure by Letters Patent of theUnited States, is as follows 1. The V-grooved drill-holder H, incombination with the stationary drill-lip rest 2, which has its line ofdrill-contact inclined to the bisecting line of the V-angle andintersecting the same near the apex of said angle, as and for thepurpose described.

2. The combination, with the drill-holder H and guide-bracket G, of aninclined and screw-threaded axis of oscillation, along which thedrill-holder is helically advanced by said screw-thread when oscillated,as above set forth.

3. In combination with the Vgrooved drill holder II, the separatedrill-stop J, and the independent V-shaped support I, which isadjnstable in a direction parallel to the axis of the drill, asdescribed,

it. The combination of the drill-holding mechanism, comprisingdrill-holder H, guidebracket G, separate drill-stop J, and theindependent adjustable V-shaped support I, with the cylindrical slide E,constructed and operated as and for the purpose set forth.

5. The combination of the drill-holding mechanism above described,supported on a cylindrical slide provided with a swivel, arranged toswing the drill to any desired part of the grinding-surface, asdescribed.

6. The drill-holder H, the stationary liprest 1 and the guide-bracket G,combined with the inclined and screw-threaded axis of oscillation G,arranged to helically advance the drill along the axis toward thegrinding-' wheel as the drilbholder is oscillated, as described.

7. The angular sliding drill-holder H and guide-bracket G, combined withthe swivelhead F, arranged. to swing the drill across thegrinding-surface in a plane parallel to the same, as and for the purposedescribed.

0. 's. WALKER.

Witnesses:

F. E. KNIGHT, W. H. OAKEs.

